/*******************************************************************************
 * Copyright (c) 2011 Google, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Google, Inc. - initial API and implementation
 *******************************************************************************/
package org.eclipse.wb.swt;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Cursor;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Display;

/**
 * Utility class for managing OS resources associated with SWT controls such as
 * colors, fonts, images, etc.
 * <p>
 * !!! IMPORTANT !!! Application code must explicitly invoke the
 * <code>dispose()</code> method to release the operating system resources
 * managed by cached objects when those objects and OS resources are no longer
 * needed (e.g. on application shutdown)
 * <p>
 * This class may be freely distributed as part of any application or plugin.
 * <p>
 * 
 * @author scheglov_ke
 * @author Dan Rubel
 */
public class SWTResourceManager {
	// //////////////////////////////////////////////////////////////////////////
	//
	// Color
	//
	// //////////////////////////////////////////////////////////////////////////
	private static Map< RGB, Color >	m_colorMap	= new HashMap< RGB, Color >();

	/**
	 * Returns the system {@link Color} matching the specific ID.
	 * 
	 * @param systemColorID
	 *            the ID value for the color
	 * @return the system {@link Color} matching the specific ID
	 */
	public static Color getColor( int systemColorID ) {
		Display display = Display.getCurrent();
		return display.getSystemColor( systemColorID );
	}

	/**
	 * Returns a {@link Color} given its red, green and blue component values.
	 * 
	 * @param r
	 *            the red component of the color
	 * @param g
	 *            the green component of the color
	 * @param b
	 *            the blue component of the color
	 * @return the {@link Color} matching the given red, green and blue
	 *         component values
	 */
	public static Color getColor( int r, int g, int b ) {
		return getColor( new RGB( r, g, b ) );
	}

	/**
	 * Returns a {@link Color} given its RGB value.
	 * 
	 * @param rgb
	 *            the {@link RGB} value of the color
	 * @return the {@link Color} matching the RGB value
	 */
	public static Color getColor( RGB rgb ) {
		Color color = m_colorMap.get( rgb );
		if( color == null ) {
			Display display = Display.getCurrent();
			color = new Color( display, rgb );
			m_colorMap.put( rgb, color );
		}
		return color;
	}

	/**
	 * Dispose of all the cached {@link Color}'s.
	 */
	public static void disposeColors() {
		for( Color color : m_colorMap.values() ) {
			color.dispose();
		}
		m_colorMap.clear();
	}

	// //////////////////////////////////////////////////////////////////////////
	//
	// Image
	//
	// //////////////////////////////////////////////////////////////////////////
	/**
	 * Maps image paths to images.
	 */
	private static Map< String, Image >	m_imageMap	= new HashMap< String, Image >();

	/**
	 * Returns an {@link Image} encoded by the specified {@link InputStream}.
	 * 
	 * @param stream
	 *            the {@link InputStream} encoding the image data
	 * @return the {@link Image} encoded by the specified input stream
	 */
	protected static Image getImage( InputStream stream ) throws IOException {
		try {
			Display display = Display.getCurrent();
			ImageData data = new ImageData( stream );
			if( data.transparentPixel > 0 ) {
				return new Image( display, data, data.getTransparencyMask() );
			}
			return new Image( display, data );
		} finally {
			stream.close();
		}
	}

	/**
	 * Returns an {@link Image} stored in the file at the specified path.
	 * 
	 * @param path
	 *            the path to the image file
	 * @return the {@link Image} stored in the file at the specified path
	 */
	public static Image getImage( String path ) {
		Image image = m_imageMap.get( path );
		if( image == null ) {
			try {
				image = getImage( new FileInputStream( path ) );
				m_imageMap.put( path, image );
			} catch( Exception e ) {
				image = getMissingImage();
				m_imageMap.put( path, image );
			}
		}
		return image;
	}

	/**
	 * Returns an {@link Image} stored in the file at the specified path
	 * relative to the specified class.
	 * 
	 * @param clazz
	 *            the {@link Class} relative to which to find the image
	 * @param path
	 *            the path to the image file, if starts with <code>'/'</code>
	 * @return the {@link Image} stored in the file at the specified path
	 */
	public static Image getImage( Class< ? > clazz, String path ) {
		String key = clazz.getName() + '|' + path;
		Image image = m_imageMap.get( key );
		if( image == null ) {
			try {
				image = getImage( clazz.getResourceAsStream( path ) );
				m_imageMap.put( key, image );
			} catch( Exception e ) {
				image = getMissingImage();
				m_imageMap.put( key, image );
			}
		}
		return image;
	}

	private static final int	MISSING_IMAGE_SIZE	= 10;

	/**
	 * @return the small {@link Image} that can be used as placeholder for
	 *         missing image.
	 */
	private static Image getMissingImage() {
		Image image = new Image( Display.getCurrent(), MISSING_IMAGE_SIZE, MISSING_IMAGE_SIZE );
		//
		GC gc = new GC( image );
		gc.setBackground( getColor( SWT.COLOR_RED ) );
		gc.fillRectangle( 0, 0, MISSING_IMAGE_SIZE, MISSING_IMAGE_SIZE );
		gc.dispose();
		//
		return image;
	}

	/**
	 * Style constant for placing decorator image in top left corner of base
	 * image.
	 */
	public static final int								TOP_LEFT			= 1;
	/**
	 * Style constant for placing decorator image in top right corner of base
	 * image.
	 */
	public static final int								TOP_RIGHT			= 2;
	/**
	 * Style constant for placing decorator image in bottom left corner of base
	 * image.
	 */
	public static final int								BOTTOM_LEFT			= 3;
	/**
	 * Style constant for placing decorator image in bottom right corner of base
	 * image.
	 */
	public static final int								BOTTOM_RIGHT		= 4;
	/**
	 * Internal value.
	 */
	protected static final int							LAST_CORNER_KEY		= 5;
	/**
	 * Maps images to decorated images.
	 */
	@SuppressWarnings( "unchecked" )
	private static Map< Image, Map< Image, Image >> []	m_decoratedImageMap	= new Map[ LAST_CORNER_KEY ];

	/**
	 * Returns an {@link Image} composed of a base image decorated by another
	 * image.
	 * 
	 * @param baseImage
	 *            the base {@link Image} that should be decorated
	 * @param decorator
	 *            the {@link Image} to decorate the base image
	 * @return {@link Image} The resulting decorated image
	 */
	public static Image decorateImage( Image baseImage, Image decorator ) {
		return decorateImage( baseImage, decorator, BOTTOM_RIGHT );
	}

	/**
	 * Returns an {@link Image} composed of a base image decorated by another
	 * image.
	 * 
	 * @param baseImage
	 *            the base {@link Image} that should be decorated
	 * @param decorator
	 *            the {@link Image} to decorate the base image
	 * @param corner
	 *            the corner to place decorator image
	 * @return the resulting decorated {@link Image}
	 */
	public static Image decorateImage( final Image baseImage, final Image decorator, final int corner ) {
		if( corner <= 0 || corner >= LAST_CORNER_KEY ) {
			throw new IllegalArgumentException( "Wrong decorate corner" );
		}
		Map< Image, Map< Image, Image >> cornerDecoratedImageMap = m_decoratedImageMap[ corner ];
		if( cornerDecoratedImageMap == null ) {
			cornerDecoratedImageMap = new HashMap< Image, Map< Image, Image >>();
			m_decoratedImageMap[ corner ] = cornerDecoratedImageMap;
		}
		Map< Image, Image > decoratedMap = cornerDecoratedImageMap.get( baseImage );
		if( decoratedMap == null ) {
			decoratedMap = new HashMap< Image, Image >();
			cornerDecoratedImageMap.put( baseImage, decoratedMap );
		}
		//
		Image result = decoratedMap.get( decorator );
		if( result == null ) {
			Rectangle bib = baseImage.getBounds();
			Rectangle dib = decorator.getBounds();
			//
			result = new Image( Display.getCurrent(), bib.width, bib.height );
			//
			GC gc = new GC( result );
			gc.drawImage( baseImage, 0, 0 );
			if( corner == TOP_LEFT ) {
				gc.drawImage( decorator, 0, 0 );
			} else if( corner == TOP_RIGHT ) {
				gc.drawImage( decorator, bib.width - dib.width, 0 );
			} else if( corner == BOTTOM_LEFT ) {
				gc.drawImage( decorator, 0, bib.height - dib.height );
			} else if( corner == BOTTOM_RIGHT ) {
				gc.drawImage( decorator, bib.width - dib.width, bib.height - dib.height );
			}
			gc.dispose();
			//
			decoratedMap.put( decorator, result );
		}
		return result;
	}

	/**
	 * Dispose all of the cached {@link Image}'s.
	 */
	public static void disposeImages() {
		// dispose loaded images
		{
			for( Image image : m_imageMap.values() ) {
				image.dispose();
			}
			m_imageMap.clear();
		}
		// dispose decorated images
		for( int i = 0; i < m_decoratedImageMap.length; i++ ) {
			Map< Image, Map< Image, Image >> cornerDecoratedImageMap = m_decoratedImageMap[ i ];
			if( cornerDecoratedImageMap != null ) {
				for( Map< Image, Image > decoratedMap : cornerDecoratedImageMap.values() ) {
					for( Image image : decoratedMap.values() ) {
						image.dispose();
					}
					decoratedMap.clear();
				}
				cornerDecoratedImageMap.clear();
			}
		}
	}

	// //////////////////////////////////////////////////////////////////////////
	//
	// Font
	//
	// //////////////////////////////////////////////////////////////////////////
	/**
	 * Maps font names to fonts.
	 */
	private static Map< String, Font >	m_fontMap			= new HashMap< String, Font >();
	/**
	 * Maps fonts to their bold versions.
	 */
	private static Map< Font, Font >	m_fontToBoldFontMap	= new HashMap< Font, Font >();

	/**
	 * Returns a {@link Font} based on its name, height and style.
	 * 
	 * @param name
	 *            the name of the font
	 * @param height
	 *            the height of the font
	 * @param style
	 *            the style of the font
	 * @return {@link Font} The font matching the name, height and style
	 */
	public static Font getFont( String name, int height, int style ) {
		return getFont( name, height, style, false, false );
	}

	/**
	 * Returns a {@link Font} based on its name, height and style.
	 * Windows-specific strikeout and underline flags are also supported.
	 * 
	 * @param name
	 *            the name of the font
	 * @param size
	 *            the size of the font
	 * @param style
	 *            the style of the font
	 * @param strikeout
	 *            the strikeout flag (warning: Windows only)
	 * @param underline
	 *            the underline flag (warning: Windows only)
	 * @return {@link Font} The font matching the name, height, style, strikeout
	 *         and underline
	 */
	public static Font getFont( String name, int size, int style, boolean strikeout, boolean underline ) {
		String fontName = name + '|' + size + '|' + style + '|' + strikeout + '|' + underline;
		Font font = m_fontMap.get( fontName );
		if( font == null ) {
			FontData fontData = new FontData( name, size, style );
			if( strikeout || underline ) {
				try {
					Class< ? > logFontClass = Class.forName( "org.eclipse.swt.internal.win32.LOGFONT" ); //$NON-NLS-1$
					Object logFont = FontData.class.getField( "data" ).get( fontData ); //$NON-NLS-1$
					if( logFont != null && logFontClass != null ) {
						if( strikeout ) {
							logFontClass.getField( "lfStrikeOut" ).set( logFont, Byte.valueOf( (byte)1 ) ); //$NON-NLS-1$
						}
						if( underline ) {
							logFontClass.getField( "lfUnderline" ).set( logFont, Byte.valueOf( (byte)1 ) ); //$NON-NLS-1$
						}
					}
				} catch( Throwable e ) {
					System.err.println( "Unable to set underline or strikeout" + " (probably on a non-Windows platform). " + e ); //$NON-NLS-1$ //$NON-NLS-2$
				}
			}
			font = new Font( Display.getCurrent(), fontData );
			m_fontMap.put( fontName, font );
		}
		return font;
	}

	/**
	 * Returns a bold version of the given {@link Font}.
	 * 
	 * @param baseFont
	 *            the {@link Font} for which a bold version is desired
	 * @return the bold version of the given {@link Font}
	 */
	public static Font getBoldFont( Font baseFont ) {
		Font font = m_fontToBoldFontMap.get( baseFont );
		if( font == null ) {
			FontData fontDatas[] = baseFont.getFontData();
			FontData data = fontDatas[ 0 ];
			font = new Font( Display.getCurrent(), data.getName(), data.getHeight(), SWT.BOLD );
			m_fontToBoldFontMap.put( baseFont, font );
		}
		return font;
	}

	/**
	 * Dispose all of the cached {@link Font}'s.
	 */
	public static void disposeFonts() {
		// clear fonts
		for( Font font : m_fontMap.values() ) {
			font.dispose();
		}
		m_fontMap.clear();
		// clear bold fonts
		for( Font font : m_fontToBoldFontMap.values() ) {
			font.dispose();
		}
		m_fontToBoldFontMap.clear();
	}

	// //////////////////////////////////////////////////////////////////////////
	//
	// Cursor
	//
	// //////////////////////////////////////////////////////////////////////////
	/**
	 * Maps IDs to cursors.
	 */
	private static Map< Integer, Cursor >	m_idToCursorMap	= new HashMap< Integer, Cursor >();

	/**
	 * Returns the system cursor matching the specific ID.
	 * 
	 * @param id
	 *            int The ID value for the cursor
	 * @return Cursor The system cursor matching the specific ID
	 */
	public static Cursor getCursor( int id ) {
		Integer key = Integer.valueOf( id );
		Cursor cursor = m_idToCursorMap.get( key );
		if( cursor == null ) {
			cursor = new Cursor( Display.getDefault(), id );
			m_idToCursorMap.put( key, cursor );
		}
		return cursor;
	}

	/**
	 * Dispose all of the cached cursors.
	 */
	public static void disposeCursors() {
		for( Cursor cursor : m_idToCursorMap.values() ) {
			cursor.dispose();
		}
		m_idToCursorMap.clear();
	}

	// //////////////////////////////////////////////////////////////////////////
	//
	// General
	//
	// //////////////////////////////////////////////////////////////////////////
	/**
	 * Dispose of cached objects and their underlying OS resources. This should
	 * only be called when the cached objects are no longer needed (e.g. on
	 * application shutdown).
	 */
	public static void dispose() {
		disposeColors();
		disposeImages();
		disposeFonts();
		disposeCursors();
	}
}